This application is based on the serendipitous finding that URMC-099 can significantly boost antiviral activities of long acting antiretroviral therapy. Developed as a novel lead first-in-class mixed lineage kinase (MLK) inhibitor under development for use against HIV-1 associated neurocognitive disorders (HAND), URMC-099 was unexpectedly found to potentiate antiretroviral actions of nanoformulated ritonavir- boosted atazanavir (nanoATV/r). This drug combination led to a marked reduction of residual HIV-1 infection. URMC-099 facilitated nanoATV/r therapeutic effects by affecting the expression of the Rab family proteins that regulate endosomal vesicle trafficking, augmenting interactions between nanoATV/r and viral particles during the viral life cycle. Herein we will determine whether MLK inhibition from URMC-099 is involved in ATV/r's actions in the endosome, or if the findings are due to effects on other kinases targeted by this agent. Our recent demonstration that URMC-099 reduces neuroinflammation and is neuroprotective against HIV-1 proteins in vivo, and that the non-selective MLK inhibitor, CEP-1347 can increase ATV accumulation and half-life in HIV-1 infected patients bodes very well for this combination of chemotherapy to safely achieve viral eradication in the CNS while protecting neural homeostasis. We propose three specific aims to further delineate these interactions: (1) We will elucidate the pathways (mechanisms) responsible for URMC-099 facilitated nanoformulated antiretroviral responses in mononuclear phagocytes (MP; monocyte-derived macrophages [MDM] and microglia) in relation to MLKs and other related kinases targeted by URMC-099 (including kinases that mediate inflammation) and determine whether virus can be eradicated or merely suppressed. (2) To assess the impact of Rab family members identified in Aim 1 on potential drug toxicities from URMC-099 and nanoART in our models of HAND. To this end, we will investigate its roles in regulating MP and synaptic networks exposed to HIV-1 neurotoxins after URMC-099 and nanoART treatment. We will use in vivo models to further understand the role of Rabs as they relate to MLK activation and synaptodendritic damage with the idea of protecting the brain against further injuries. Finally, in (3) we will validate the utility of nanoformulated antiretrovral therapy (nanoART) and URMC-099 in clearance of persistently infected viral reservoirs in the CNS in our humanized CD34 engrafted model of neuroAIDS. Together, these aims will advance our approach to eradication of long-lived persistent infection of CNS MP while preserving synaptic architecture and function in disease.